Elbow and lock mechanism for artificial arms



y 1951 G. M. MOTlS 2,553,830

ELBOW AND LOCK MECHANISM FOR ARTIFICIAL ARMS Filed May 7, 1949 3 Sheets-Sheet 1 I N V EN TOR. 6//cr/ M NOf/b' y 1951 G. M. MOTIS 2,553,830

ELBOW AND LOCK MECHANISM FOR ARTIFICIAL ARMS Filed May '7, 1949 5 Sheets-Sheet 2 i 35 a If 4 56 2 7/ 0 6/ /o6 M /O5 /07 //0 72 5/ HTTG/t /VEK May 22, 1951 G. M. MOTlS ELBOW AND LOCK MECHANISM FOR ARTIFICIAL ARMS 5 Sheets-Sheet Filed May 7, 1949 Patented May 22, 1951 with 'llTI-ES' OFFICE ELBOW' AND LOCK MECHANISM FOR ARTIFICIAL ARMS Gilbert M. Motis, Burbank, Calif., assignor, to Northrop; Aircraft, llnc., Hawthorne, Calif., a corporation of California Application May 7, 1949, Serial No. 91,992

arrangement gives the amputee a choice of operating means, and enables him to lock or unlock the elbow by whichever of the operating means is .more convenient to. use at the time. Another advantage of this feature is that the forearm button can be/ used to override the shoulder control in maintaining the elbow in the unlocked condition, so that the elbow will not be locked inadvertently by an unintentional tug on the shoulder harness of the lock control when the arm isv Swinging, as while walking or driv-- mg.

Another important object of the invention is to provide an elbowlock having a minimum number ofparts, and in which thereare no critical dimensional tolerances. The elimination of critical tolerances is particularly important, as it makes possible the use of sheet metal shell con struction in the upper and lower elbow housings, which provides great strength with the minimum weight. heretofore blocking the use of sheetmetal shell construction for the elbow housings has been the relatively wide range of dimensional variation obtained in the finished housings, which are usually made up of two or more stampings that are. welded together. This excessive variation in housing dimensions cannot be tolerated in the conventional elbow lock, where certain of the dimensional tolerances are relatively-critical, but provides no particular problem inthe case of the present elbow lock, which is designed to accommodate itself to the dimensional variations of the sheet metal housings. It is a further object of the present invention, therefore, to provide anelbow lock particularly adapted for usein an elbow joint wherein the upper and lower'housings. are of sheet metal shell construction.

Other advantageous features of the invention resultingfrom the use of sheet metal shell housings are: (1) the locking mechanism is fully enclosed within the elbow housings, giving a smooth exterior which will not catch on clothing; (2) large area bumpers of soft rubber can. be used to limit the travel of the lower arm in both, directions, giving a quiet, more resilient One of the chief problems 2. bumper action; and 3') ings can be used on the elbowhinge pivot.

Another advantage. of the present inventionis that ample clothing clearance is obtained at the.

inside of the elbow, even when the arm is. fully flexed; and such clearance is obtained without, the use of cut-outs in the forearm portion, which, seriously weaken. the arm. This is accomplished. by moving the elbow hinge. axis forwardly to a point closely adjacent the front side. of the arm,- and flattening the arm cross section where it.

joins the elbow housingsto a substantially e1- liptical cross section.

The foregoing and other objects and advantages of the present invention will become ape parent to those skilled, in the art upon consideration of the following detailed description of.

the preferred embodiment thereof, reference be: ing had to the accompanying drawings, wherein:

Figure 1 is a perspective view of an artificial arm embodying the principles of my invention;

Figure 2 is an; enlarged, partially cutaway view of the elbow joint, showing certain details ofthe forearm lock control;

Figure 3 is a sectional view through the forearm lock control button, taken at 3--3 in Figure 2;

Figure 4 is a transverse section through the elbow at the axis of the hinge pivot;

Figure 5 is a fragmentary View of a detail, taken at the section line 5-5 in Figure 4;.

Figure 6 is a sectional view through the elbow, taken at 65 in Figure 4;

Figure 7 is a sectional view through the al: ternator device, taken at 1'l in Figure 6;

Figure 8'is a sectional view through the same, taken at 88 in Figure 7;

Figure 9 is another sectional view taken at 99 in Figure 7, showing the alternator in the elbow locking position;

Figure 10 is a view similar to Figure 9, but showing the alternator device in the unlocking position; and

Figure 11 is an exploded perspective View of the parts in the alternator device.

In the drawings, the arm is designated in its entirety by the reference numeral it and is seen to comprise an upper arm portion i l and a lower arm portion l2, which are connected together for relative swinging movement by an elbow l3. Mounted on the .distal end of the lower arm portion I2 is a normally closed hook M which is opened by a Bowden cable control Wire l5. The control wire I5 passes through a length of springwound conduit 16 which is attached by a leather large diameter bearloop ll to the forearm portion l2 adjacent the elbow. Further up on the arm, the wire passes through another length of spring-wound conduit 28 which is attached to the upper arm portion H by a detachable anchor fitting 2!. Fixed to the upper end of control wire i5 is a yoke 22 to which a leather strap 23 is attached, said strap being adapted to be secured. to the usual shoulder harness so that a forward movement of the shoulder produces a pull on the control wire l5 which may either open the hook id or raise the forearm E2. If the elbow is locked, the pull on the control wire opens the hook against the tension of a rubber band 24; whereas, if the elbow is unlocked, a pull on the control wire will lift the forearm unless the force required to lift the forearm exceeds the force required to open the hook.

Both the upper arm portion l l and lower arm portion l2 are preferably, although not necessarily, formed of plastic shell construction, built up by laminating fabric such as cotton stockinet over suitable plaster forms, impregnating the fabric with a liquid resin, and then curing the resin in an oven. The upper arm portion H is the stump socket and is therefore shaped to provide a snug fit over the stump. D-rings 24 are attached by straps 25 to the inner and outer sides of the upper arm portion Ii, and straps of the harness pass through the D-rings to hold the arm is on the stump.

The elbow i3 is comprised of an upper elbow housing .20 and a lower elbow housing 3%, which are connected together for relative swinging movement by a transversely extending tubular shaft 32. Each of the housings 39, 3! is preferably formed of sheet metal stampings which are welded together to form hollow shells. The upper housing 31} is provided with an end flange 33 of elliptical shape which is inserted into the elliptically curved end of the upper arm shell ii and secured thereto by rivets or screws 3 The end of the arm shell Ii is formed so that when the arm is hanging down at the side, the major axis of the ellipse is turned inwardly at an angle ,3

of about 15 to the transverse body plane, whereby the plane of movement of th forearm is inclined inwardly across the front of the body, at an angle approximating the plane of movement of the natural arm. The tubular pivot shaft 32 extends through the upper elbow housing 38 parallel to the major axis of the ellipse but spaced forwardly therefrom, so that the axis of the shaft is closely adjacent the front side of the elbow.

The front side of the upper elbow housing is formed with a generally cylindrically curved portion of relatively small radius which is concentric with the pivot shaft 32, and projecting outwardly from the side of the curved portion 35 opposite the flange 33 is a flat shelf portion 36, to which is cemented a sponge rubber "down bumper 31 of relatively large area. The back side of the housing 39 has the configuration of a portion of an oblate spheroid, the axis of revolution of which is the axis of shaft 32. Thus, the circularly curved portion 49 (Figure 6) of the housing 33 is also concentric with the shaft 32, but of considerably larger radius than the curved portion 35. The flattened sides of the housing 30 have inwardly flanged holes ii formed therein, into which bushings 42 are inserted and soldered, and the ends of the tubular shaft 32 are journaled in these bushings.

The lower elbow housing 3! is likewise provided with an end flange 43 of elliptical shape which is inserted into the proximal end of the forearm shell i2 and secured thereto by rivets or screws 44. As in the case of the upper arm II, the ellipse of the forearm shell [2 is also disposed with its major axis parallel to the axis of the tubular shaft 32. The portion of the housing 3! projecting beyond the end of the forearm shell 52 forms a saddle 45 which surrounds the back side of the upper elbow housing 30 and fits closely over the flattened sides of the latter. An inwardly turned lip 36 closes the clearances between the lower elbow housing 3| and the back side of the upper elbow housing 30, while another lip ll extends in toward the curved surface 35 on the front side of the upper elbow housing to close the gap between them.

The tubular pivot shaft 32 is non-rotatably secured to the lower elbow housing 3| by means of two serrated plugs and 51 which fit into the ends of the shaft. The serrations on the outer peripheries of the plugs 50, 5| engage companionate serrations 52 on the inside of the shaft 32 at the extreme ends thereof, and the ends of the plugs project beyond the ends of the shaft 32 and are received within internally serrated rings 53 which are soldered or welded to the inside surfaces of the lower elbow housing 31 at opposite sides thereof. Each of the rings 53 has a radially outwardly extending tongue 54 which is welded at 55 to the lower elbow housing 3|, so that the rings 53 are strongly held thereby against rotation with respect to the housing.

The serrated plugs 50, Si are slidable axially between the position shown in Figure 4, wherein both the rings 53 and internal serrations 52 on the ends of the tubular shaft 32 are engaged by the serrated plugs, to another position Wherein the plugs are shifted inwardly so that they are completely enclosed within the ends of the tubular shaft, thereby releasing the lower elbow housing 3|. The serrated parts 50, 5| are pulled outwardly by screws 55 which extend through indented holes in the side of the housing 3!, and are threaded into tapped holes 61 in the center of the plug.

The elbow lock mechanism is comprised of two cooperative locking members, preferably in the form of an arcuate sector gear 62 which is welded or otherwise suitably fixed to the inside of the upper elbow housing 38 concentric with the pivot shaft 32, and a swingable plunger gear 63 which is mounted on the tubular shaft 32 for rotation therewith. The plunger gear 63 has a cylindrical shank portion 64 which is slidably received within a bore 65 in a plunger gear housing 65, said housing having a transversely extending circular aperture 72! formed therein, through which the shaft 32 projects. The housing 66 is secured against rotation relative to the shaft 32 by means of a tubular key H which is disposed within the shaft 32 and projects downwardly through an opening 72 into the bore 65 of housing 66. The shank of the plunger gear 63 has a reduced-diameter portion 13 which extends up into the tubular key 1! and is slidable therein.

The tubular key H terminates at its top end in a tapered nose M having an opening 15 formed in its extremity. A set screw '16 which is threaded into a tapped hole 89 in the top of housing 65 and passes downwardly through another hole 8| in the shaft 32 engages the opening 15 in the end of the tubular key to hold the upper end of the latter in place. The housing 66 is thus attached to the top of the tubular shaft 511 g 32 by the set screw. iii, and to the bottom of the shaft by the tubular key l 1, thereby locking the housing solidly to the shaft so as to rotate therewith. An up bumper ll of sponge rubber is cemented to the front side of the housing 85 and is engageable with the underside of the shelf 36 to limit, the fiexion movement of the forearm.

A compression coil spring 8'2 within the tubular key 1! bears downwardly against the topend of the shank of plunger gear 63, pressing the latter downinto engagement with the sector gear 62 to lock the elbow. The plunger gear 63 may be lifted out of engagement with the sector gear 62 to unlock the elbow by means of either a forearm lock control or a shoulder lock control, both of which will now be described.

The forearm lock control is operated by a push button 85 projecting downwardly from the underside of the forearm shell i2. The button 85 is mounted on the outer end of a short length of rod 86 which extends through a hole 3? in a plate 95 that is secured by screws 8! to the outside of the arm shell. The opposite sides of the rod 8% are flattened at 92, as best shown in Figure 3, and the edges of the hole 8'. in plate 99 are correspondingly shaped so as to prevent the push button from turning. A pin 93 extends transversely through the rod 85: and projects outwardly from both of the flat sides 92; pin engaging the inside surface of the plate 9:? to limit the outward movement of the push button. A notch as is also provided in the forward side of the rod 86 di ectly beneath the butts-n 85, and this notch is engageable over the lip of the hole 8? to hold the push button in the depressed position, as shown at 85 in Figure A tapped hole extends lengthwise into the rod 85 from the inner end thereof, and threaded into this hole is a screw fitting 95 having a yoke 96 at the top end thereof which is connected by a pin 9i to one end of a lever 98. The lever 98 extends toward the elbow it between the sheet metal side wall of the housing 3| and the serrated ring 53 at the left hand end of the elbow, as viewed in Figure Lever 98 is pivoted for swinging movement about a pin 99 which extends through alined holes in the housing 3| and ring 53 a short distance out wardly beyond the axis of shaft and the rear end of the lever is bent upwardly and projects L beyond the pin. $9 to a point below the axis of the shaft. Formed in this rearward extension of the lever 88 parallel to the sides thereof is an elongated slot Hi5 which receives the outer end of a fulcrummed lever I06.

The lever Hi6 extends into the tubular shaft 32 through, an off-centered hole 58'! in the inner end wall of the serrated plug 5%), and has circumferential beads I533 formed thereon at either side of the hole 19?, whereby the lever is constrained against axial movement with respect to the plug. The inner end. of the lever we extends through a longitudinally extending slot H8 in the tubular key ii and into a hole H! in the shank portion 53 of the plunger gear 63. The slot Ho permits the inner end of the lever N36 to be raised from the position shown in solid line in Figure 4 to the position shown in phantom line, thereby lifting the plunger gear E3 out of engagement with the sector gear 62.

Normally, the plunger gear 36 is urged outwardly into engagement with the sector gear 62 by sprin 82, and the lock control push button 85 is pressed outwardly by a spring I 45 which is anchored at one end to a tab M6 on the flange 43,

and passes and is attached at its other end to the lever 98. To release the elbow lock, the push button is pushed inwardly until the notch 94 catches onto the plate 90. This raises the right hand end (Figure 2) of the lever 98 about the pivot pin 99,

and causes the left hand end of the lever to swing downwardly, pulling the outer end of the lever 105 down with it. Since the lever IE5 is fulcrumed intermediate its ends on the serrated plug 58, the inner end of the lever is thus raised,

lifting the plunger ear 63 out of engagement with the sector gear 62, and thereby releasing the elbow look so that the forearm member is free to swing relative to the upper arm.

Shoulder control of the elbow lock is obtained by exerting successive pulls on a flexible control wire I29, the upper end of which is attached to an over-travel spring |2l which is connected, in

turn, to a strap [22. The strap I22 is adapted to be attached to. the usual shoulder harness so that a shrug of the shoulder produces a pull on the wire I29. The over-travel spring I2! is designed to transmit the tension required to operate the elbow look without stretching, but to yield whenever an excessive force is applied, and thereby protects the relatively light control wire 23 from bein broken.

The lower end of the control wire I28 enters is upper elbow housing 321 through a small hole i2 3 and is operatively connected to a shoulder control lock alternator I25 which is operatively connected, in turn, by a coupling cable 26v toa pin l2! projecting laterally from the shank portion 64 of the plunger gear. The pin i2! extends laterally outward through a slot iSil in the housing 66, and is slidable therein so, that the plunger gear is permitted a limited amount of axial movement but is constrained against rotation with respect to the housing. The cable I29 extends through and is slidable within a springwound flexible conduit l3l which is wrapped loosely around the tubular shaft 32 and is attached at its opposite ends to the housing 66 and bracket L32 of the alternator I25, respectively. The bracket I32 is provided on" opposite sides thereof with outwardly turned mounting flanges 533 which are secured by screws I34 to cars I31 projecting downwardly from the inside surface of the housing shell, as seen in Figure 6. The

vbracket I32 is U-shaped, and extending transversely between the side portions thereof is a shaft I35 having a reduced-diameter portion 536.

Journaled on the shaft H35 and slidable axiallythereon is a sheave wheel Hill having a ciri cumferential grove I4! on its periphery, in which the control wire I20 is laid. The sheave wheel Hill is provided with an angular corner portion I42 which is engageable with the bottom of the bracket I32 to limit the clockwise (Figure 8) rotation of the wheel to approximately from the position shown. The control wire lZii is guided into the grove IM of the sheave wheel by a composition fiber block i38 which is held between upstanding ear I39 on bracket I32, and is wrapped around the wheel and. attached thereto in any suitable manner. A torsion spring M3 encircles the shaft l35 between the sheave wheel M9 and the right hand side member (Figure 7) of the bracket 432; one end of said spring being bent parallel to the axis of the coils and inserted into a hole in the adjacent side of the sheave wheel, and the other end thereof extending tangentially to the coils and having a hook Hi l provided thereon which is hooked over oneedgeof 7.5 the adjacent bracket side.

Projecting axially from the other side of the sheave wheel I40 are four pins I45 which are spaced equi-distantly from the axis of rotation, and which are also spaced apart 90 from one another. The ends of pins I45 are engageable with two inclined ramp surfaces I45 and I4? on the adjacent end of a cam member I50 which is journaled on the reduced-diameter portion I35 of the shaft 535. The cam member I50 is generally elliptical in shape, with two diametrically opposite high portions I on its periphery, separated by two low portions I52. The inclined ramps I46, I41 terminate in shoulders I53 and I54, respectively, which are engageable by two of the pins I45 when the sheave wheel I40 is turned in the counterclockwise direction, as viewed in Figure 10. With the pins I45 thus abutting against the shoulders I53, I54, the cam member I50 is turned with the sheave wheel I40 for 90 of rotation. As the pull on control wire I20 is relaxed, the torsion sprin I43 returns the sheave wheel I40 to its initial position, during which time the pins I45 ride up on the inclined ramps I48, I47 until they pass the shoulders I53, I54 and drop down behind the latter in position to drive the cam member I50 again the next time that the sheave wheel I40 is rotated by a pull on control wire I20. The frictional drag of the pins I45 over the inclined ramps I46, :4? creates a tendency on the part of the cam member $50 to turn with the sheave wheel I 40, and this tendency is resisted by a pair of dimples I55 (Figure 7) in the side wall of the bracket I32 which are engageable in a longitudinally extending groove I56 in the side of the cam member. When the grove I56 is thus seated on the dimples I55, the cam member is yieldingly restrained against turning with the sheave wheel, but when sufiicient turning force is applied to the cam member, the latter can be forced to override the dimples I55. A soft rubber O-ring I57 encircles the reduced-diameter portion I36 of the shaft between the cam member I50 and sheave wheel I40, and serves to cushion the impact of the latter as it drops against the cam member under the pressure of spring I43. The axial movement of sheave wheel I40 to accommodate the climbing movement of the pins up the inclined ramp is allowed by the free-sliding support of the sheave wheel on the shaft I35.

Pivotally mounted on a pin I50 adjacent the periphery of the cam member I50 is a lever arm IBI, the top end of which is connected at I52 to the coupling cable I25. The lever arm ISI is swingable in the plane of rotation of the cam member I50, and is movable between the two positions shown in Figures 9 and 10. The lever arm takes the position shown in Figure 9 when it is engaged by one of the low portions I52 of the cam and is moved over to the position shown in Figure when engaged by one of the high portions I5I. Since the other end of the coupling cable I26 is connected to pin I2? on the plunger gear 63, it will be seen that a pull on cable I26 acts to lift the plunger gear out of engagement with the sector gear 52. Thus, when the lever arm i6! is swung over to the position shown in Figure 10, the plunger gear is lifted out of engagement with the sector gear to unlock the elbow. When the lever arm ISI is restored to the position shown in Figure 9, the plunger gear is permitted to move back down into engagement with the sector gear under the urging of spring 82.

From the foregoing description, it will be seen ill that each time that a pull is exerted on the control wire I20 by a shoulder shrug, the sheave wheel I40 is turned a quarter turn against the torsional resistance of spring I43, causing the pins I 45 to drive the cam member I50 through a quarter turn. When the tension is relaxed on the control wire I20, the sheave wheel I40 is restored by spring M3 to its initial position, in readiness to engage the cam I50 and drive the same through another quarter turn the next time that tension is applied to the control wire by another shoulder shrug. Since each shoulder shrug produces a quarter turn of the cam member I50 it will be seen that the lever arm I 6| is engaged first by the high portions I5I of the cam and then by the lower portions I52 thereof, alternately locking and unlocking the elbow.

The method of operation is believed to be selfevident from the foregoing description. Whenever the amputee wishes to lock or unlock the elbow, he has the choice of using either the shoulder lock control or the forearm lock control, depending upon which is the more convenient to use at the moment. Whenever the amputee wishes to maintain the elbow in the unlocked condition, so that the arm will swing freely in a natural manner while walking, and to prevent inadvertent locking due to an unintentional pull on the control wire I20, he can override the shoulder lock control by pressing the forearm button inwardly and catching the notch 94 on the plate 90. The plunger gear 63 is then lifted and held out of engagement with the sector gear 62, and the plunger gear is therefore unaffected by tension in the coupling cable While I have shown and described in considerable detail what I believe to be the preferred form of my invention, it is to be understood that such details are not restrictive and that various changes may be made in the shape and arrangement of the several parts thereof without departing from the broad scope of the invention, as defined in the appended claims.

I claim:

1. In an artificial arm having upper and lower arm portions connected together at the elbow for relative swinging movement, an elbow lock comprising a stationary arcuate sector gear fixed to said upper arm portion concentric with the pivot axis of said elbow, a swingable gear member attached to said lower arm portion for movement therewith, said swingable gear member being movable radially with respect to said pivot axis between a locked position in engagement with said sector gear and an unlocked position, an operating button on said lower arm portion connected with said swingable gear member for shifting the same from one of said positions to the other, harness-connected means for shifting said swingable gear member from one of said positions to the other responsive to a shoulder shrug, and means for securing said operating button in the elbow-unlocked position, whereby said harness-connected means is prevented from inadvertently locking the elbow by an unintentional. tug on the shoulder harness.

2. In an artificial arm having upper and lower arm portions connected together at the elbow for relative swinging movement, an elbow lock comprising a stationary arcuate sector gear fixed to said upper arm portion concentric with the pivot axis of said elbow, a swingable gear member attached to said lower arm portion for movement therewith, said swingable gear member being movable radially with respect to said pivot axis between a locked position in engagement with said sector gear and an unlocked position, an alternator device connected to said swingable gear member and operable to shift the same alternately to one and then the other of said positions upon successive operations thereof, and means for operating said. alternator device by a shoulder shrug.

3. In an artificial arm having upper and lower arm portions connected together at the elbow for relative swinging movement, an elbow lock comprising a stationary arcuate sector gear fixed to said upper arm portion concentric with the pivot axis of said elbow, a swingable gear member attached to said lower arm portion for movement therewith, said swingable gear member being movable radially with respect to said pivot axis between a locked position in engagement with said sector gear and an unlocked position, an

operating button projecting from said lower arm portion, and linkage means connecting said button with said swingable gear member, whereby the latter is shifted to said unlocked position when the button is pressed inwardly, and is shifted to said locked position when said button is moved out to its extended position.

4. In an artificial arm having upper and lower arm portions connected together at the elbow for relative swinging movement, an elbow lock comprising a stationary member fixed to said upper arm portion adjacent the pivot axis of said elbow, a swingable member attached to said lower arm portion to cooperate with said stationary member, one of said members being movable between a locked position in engagement with the other member and an unlocked position, an alternator device comprising a lever arm pivoted for swinging movement, means connecting said lever arm to said one member-for shifting the latter between said locked and unlocked positions when the lever arm isrockecl between two positions, a rotatable cam member engageable with said lever arm to move the same from one of said positions to the other as the cam member is progressively advanced by equal angular incre ments, and means connected to a shoulder harness for advancing said rotatable cam member by a shoulder shrug.

5. In an artificial arm having upper and lower arm portions connected together at the elbow for relative swinging movement, an elbow lock comprising a stationary member fixed to said upper arm portion adjacent the pivot axis of said elbow, a swingable member attached to said lower arm portion to cooperate with said stationary member, one of said members being movable between a locked position in engagement with the other member and an unlocked position, an alternator device comprising a lever arm pivoted on said upper arm portion for swinging movement, means connecting said lever arm to said one member for shifting the latter between said locked and unlocked positions when the lever arm is rocked, a rotatable cam member engageable with said lever arm to rock the same, a pulley arranged coaxial with said cam member and having a shoulder harness connection whereby the pulley is rotated in one direction responsive to a shoulder shrug, means on said pulley engageable with said cam member to turn the latter in said one direction of rotation to advance the cam member by a predetermined angular increment, and a torsion spring connected with said pulley to return the same to its initial position when the shoulder is relaxed.

6. In an artificial arm having upper and lower arm portions, a transversely disposed tubular shaft fixed to said lower arm portion and journaled for rotation with respect to said upper arm portion, a sector gear fixed to said upper arm portion concentric with said shaft, a plunger gear slidably supported on said shaft for movement in the radial direction, a sprin urging said plunger gear into engagement with said sector gear, a fulcrumed lever extending into said tubu lar shaft from one end thereof and engaging said plunger gear, and means engaging the outer end of said lever for rocking the same on its fulcrum to lift said plunger gear out of engagement with said sector gear.

7. In an artificial arm having upper and lower arm portions, a transversely disposed tubular shaft fixed to said lower arm portion and journaled for rotation with respect to said upper arm portion, a sector gear fixed to said upper arm? portion concentric with said shaft, a plunger gear slidably supported on said shaft for movement in the radial direction, a spring urging said plunger gear into engagement with said sector gear, a fulcrumed lever extending into said tubular shaft from one end thereof and engaging said plunger gear, a lock control push button projecting from said lower arm portion, and a lever arm pivoted on said lower arm portion adjacent said shaft, one end of said lever arm being connected to said push button and the other end thereof being connected to said fulcrumed lever, whereby the latter is rocked on its fulcrum to lift said plunger gear out of engagement with said sector gear when said push button is depressed.

8. In an artificial arm having upper and lower arm portions, an upper elbow housing fixed to said upper arm portion, a lower elbow housing fixed to said lower arm portion, a transversely disposed tubular shaft journaled in said upper elbow housing and fixedly attached to said lower elbow housing to rotate therewith, a sector gear fixed to said upper elbow housing concentric with said shaft, a plunger gear housing nonrotatably mounted on said shaft, a plunger gear slid-ably disposed within said plunger gear housing for movement in the radial direction, a spring urging said plunger gear into engagement with said sector gear, a fulcrumed lever extending into said tubular shaft from one end thereof and engaging said plunger gear, a lock control push button projecting from said lower arm portion, a lever arm pivoted on the inside of said lower elbow housing adjacent said shaft, one end of said lever arm being connected to said push button and the other end thereof being connected to said fulcrumed lever, whereby the latter is rocked on its fulcrum to lift said plunger gear out of engagement with said sector gear when said push button is depressed, harness-connected means for lifting said plunger gear out of engagement with said sector gear responsive to a shoulder shrug, and a catch for securing said push button in the elbow-unlocked position, whereby said harness-connected means is prevented from inadvertently locking the elbow by an unintentional tug on the shoulder harness.

9. In artificial arm having upper and lower arm portions. an upper elbow housing fixed to said upper arm portion, a lower elbow housing xed to said lower arm portion, a transversely disposed shaft journaled in said upper elbow housing and fixedly attached to said lower elbow housing to rotate therewith, a sector gear fixed to said upper elbow housing concentric with said shaft, a plunger gear housing non-rotatably mounted on said shaft, 2. plunger gear slidably disposed within said plunger gear housing for movement in the radial direction, a spring urging said plunger gear into engagement with said sector gear, a pin projecting laterally from said plunger gear, a tension-transmitting control wire attached at one end to said pin, and means connected to the other end of said control wire for exerting a pull thereon responsive to a shoulder shrug, whereby said plunger gear is lifted out of engagement with said sector gear.

10. In an artificial arm having upper and lower arm portions, an upper elbow housing fixed to said upper arm portion, a lower elbow housing fixed to said lower arm portion, a transversely disposed shaft journaled in said upper elbow housing and fixedly attached to said lower elbow housing to rotate therewith, a sector gear fixed to said upper elbow housing concentric with said shaft, a plunger gear housing nonrotatably mounted on said shaft, a plunger gear slidably disposed within said plunger gear housing for movement in the radial direction, a spring urging said plunger gear into engagement with said sector gear, a pin projecting laterally from said plunger gear and sliding within a slot in said plunger gear housing, a tension-transmitting control wire attached at one end to said pin, and a shoulder-controlled alternator device mounted on said upper elbow housing and operatively connected to the other end of said control wire, whereby said plunger gear is lifted and held out of engagement with said sector gear by a shoulder shrug, and then released and lowered into engagement with said sector gear by the next succeeding shoulder shrug.

11. In an artificial arm having upper and lower arm portions, an upper elbow housing fixed to said upper arm portion, a lower elbow housing fixed to said lower arm portion, a transversely disposed tubular shaft journaled in said upper elbow housing and fixedly attached to said lower elbow housing to rotate therewith, a sector gear fixed to said upper elbow housing concentric with said shaft, a plunger gear housing nonrotatably mounted on said shaft, a plunger gear slidably disposed within said plunger gear housing for movement in the radial direction, a spring urging said plunger gear into engagement with said sector gear, a fulcrumed lever extending into said tubular shaft from one end thereof and engaging said plunger gear, a lock control push button projecting from said lower arm portion, a lever arm pivoted on the inside of said lower elbow housing adjacent said shaft, one end of said lever arm being connected to said push button and the other end thereof being connected to said fulcrumed lever, whereby the latter is rocked on its fulcrum to lift said plunger gear out of engagement with said sector gear when said push button is depressed, a pin projecting laterally from said plunger gear, a tension-transmitting control wire attached at one end to said pin, a shoulder-controlled alternator device mounted on said upper elbow housing and operatively connected to the other end of said control wire, whereby said plunger gear is lifted and held out of engagement with said sector gear by a shoulder shrug, and then released and lowered into engagement with said sector gear by the next succeeding shoulder shrug, and a catch for securing said push button in the elbow-unlocked position, whereby said shoulder-controlled alternator device is prevented from inadvertently locking the elbow by an unintentional shoulder shrug.

12. In an artificial arm having upper and lower arm portions, an elbow joint comprising a hollow sheet metal upper elbow housing attached to said upper arm portion, a hollow sheet metal lower elbow housing attached to said lower arm portion and enclosing the outer end of said upper elbow housing, a tubular shaft extending transversely through said upper elbow housing and journaled for rotation therein, means for non-rotatably connecting said lower elbow housing to the ends of said shaft, an arcuate locking member fixed to the inside surface of said upper elbow housing concentric with said shaft, another locking member extending diametrically through said tubular shaft and movable radially with respect thereto between positions of engagement and disengage ment with said arcuate member, operating means disposed within said tubular shaft and projecting from one end thereof, said operating means being engageable with said other locking member closely adjacent the axis of the tubular shaft for shifting said other locking member between engaged and disengaged positions, and control means connected to the projecting end of said operating means for actuating the same.

GILBERT M. MOTIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re.14,939 Anderson et a1. Aug. 31, 1920 423,840 Ulmer et a1 Mar. 18, 1890 1,273,461 Corley July 23, 1918 1,365,646 Adams Jan. 18, 1921 FOREIGN PATENTS Number Country Date 133,344 Great Britain Oct. 16, 1919 303,664 Germany Feb. 11, 1918 OTHER REFERENCES Terminal Research Reports, by Committee on Artificial Limbs of the National Research Council. A copy was received in Div. 55 of the Patent Ofiice November 13, 1947, pages 22, 23.

Veterans Administration pamphlet 10-16 of September 1947, News About Artificial Arm Developments, pages 8 and 9. A copy is in Div. 55 of the Patent Ofiice. 

